This invention relates to composite sheet coatings as thermal barriers and more particularly to providing rocket motors with an ablative insulating covering or cook-off coating which inhibits heat transfer for safety purposes.
Previous attempts to provide cook-off coatings for rocket motors has resulted in coatings that had insufficient strength or insulating properties to provide the necessary protection time and margin of safety against fire due to outside sources or burning propellant. Intumescent chemicals have been used before as thermal barriers between layers of a propellant for preventing reignition of a quenchable grain that has been quenched to extinguish the burning thereof. Also, inorganic flakes of mica or glass have been used in high temperature resistant, high voltage insulating sheet material. Nevertheless, none of the prior art insulators have provided a suitable cook-off coating for providing safety and protection of rocket motors or similar devices during fire hazards.
It is an object of the present invention to provide an externally applied, ablative thermal barrier coating in a flexible sheet-form.
It is another object of the invention to provide a cook-off coating for rocket motors.
Still another object of the invention is to provide a novel composite coating which serves as a safety thermal barrier for rocket motors.
A further object of the invention is to provide a method for wrapping and joining composite thermal insulating materials to rocket motors to form protective thermal barriers thereon.
Further objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.